Method and an Apparatus for Filling of Packages

ABSTRACT

A method of reducing the proportion of oxygen in an at least partly formed package before product is filled into the package in a filling station in a filling machine, where the package comprises a tube-shaped blank of packaging material, the blank being closed in a first end and open in a second end. The method involves, during transport of the package to the filling station from an immediately preceding station in the filling machine, passing the package beneath a supply means for inert gas, and when the package passes the supply means generating a gas pulse in a direction down into the package. An apparatus is provided for reducing the method into practice.

TECHNICAL FIELD

The present invention relates to a method of reducing the proportion ofoxygen in an at least partly formed package before product is filledinto said package in a filling station in a filling machine. Saidpackage comprises a tube-shaped blank of packaging material, the blankbeing sealed in a first end and open in a second end.

BACKGROUND ART

Within the food industry, it is common practice to pack drinks and otherproducts with a higher viscosity in packages produced from laminates ofpaper and plastic. In many cases, the packaging laminates also includean oxygen gas barrier such as, for example, an aluminium foil, in orderto make it possible to achieve a longer shelf-life for oxygen-sensitiveproducts, in particular fruit juices.

One common package type is produced in a filling machine in thatflat-laid, tube-shaped packaging blanks are raised and sealed in theirone end, either by folding and sealing of the end region or in that atop of plastic is injection moulded direct on the end region. Thepackage is subsequently transported with its open end directed upwardsand is filled in a subsequent filling station. In certain cases, thepackage also passes a sterilisation station before the fillingoperation. After the filling, the package is folded and sealed. Theapplicant markets these types of packages under the trademarks TetraTop® and Tetra Rex®.

In almost all long-term packing of food products, the quantity of oxygengas in the filled and sealed package is a crucial question. Many foodsmay be damaged if there is an abundance of oxygen gas in the package, orif oxygen gas can penetrate into the package during storage. In order tominimise the quantity of oxygen gas in the sealed package, it is,therefore, common practice to attempt to replace the air in the gasvolume, normally called the “head space”, before the package is closedand sealed. The gas volume is that part of the package which is notfilled with product. One common method of reducing the quantity ofoxygen gas in the gas volume is to blow in an inert gas, preferablynitrogen gas, into the open end of the package immediately afterfilling, but before the package is sealed. This process is normallycalled “head space flushing”. The air uppermost in the package, in theregion above the level of the product, is thereby forced out andreplaced by nitrogen gas which does not react with the product. Such amethod is described, for example, in the applicant's own internationalpatent publication carrying serial number WO 2004/039677. A similarsolution is disclosed in U.S. Pat. No. 5,896,727.

For the same reason, it is also known in the art to maintain nitrogengas-rich ambient surroundings around the filling station before, duringand after filling. Such a solution is described int. al. in U.S. Pat.No. 2,917,880 where the air in the package is first sucked out through anozzle which is placed over the open end of the package. Thereafter,nitrogen gas is blown in and the filling is commenced. U.S. Pat. No.3,477,192 disclosed another solution where a hood is placed over thefilling station, the hood being largely filled with nitrogen gas inorder to minimise the quantity of oxygen which accompanies the contentsdown into the packages on filling, and reduces frothing of the product.Further, U.S. Pat. No. 4,870,801 describes an advanced system forsupplying, in different stages, inert gas or liquid into packages beforeand/or after filling in order to reduce the quantity of oxygen in thefinished package. These solutions display the drawback that they requireconsiderable, and in certain cases also complicated, equipment.Similarly, one or more process steps are required for the aspiration ofthe nitrogen gas, i.e. the package is indexed up to and from specialgassing stations, which takes time. The solution involving a hood asdisclosed in U.S. Pat. No. 3,477,192 moreover requires a considerablequantity of nitrogen gas. Taken as a whole, these prior art solutionsare relatively costly.

BRIEF SUMMARY OF THE INVENTION

One object of the present invention is to realise a method of rapidlyand simply at least partly filling a package with inert gas beforeproduct filling is commenced, with a view to reducing the quantity ofoxygen gas in the finished package. A further object of the presentinvention is also to employ as little inert gas as possible.

These objects are attained according to the present invention by meansof a method which is characterised by the steps that the package, duringtransport to said filling station from the immediately preceding stationin the filling machine, passes beneath supply means for inert gas, andthat, when the package passes said supply means, a gas pulse is realisedin a direction down into said package. By such means, the air in thepackage is replaced by inert gas which remains in the package during thefilling cycle. The filling normally gives rise to the formation ofbubbles and froth in the product, and these bubbles migrate slowlyupwards in the product and reach the gas volume uppermost in thepackage. These bubbles are normally not accessed by “head spaceflushing” since the bubbles take a while to reach the surface and, as aresult, have not reached the gas volume when this “flushing” takesplace. If, hence, there is air in the package on filling, the bubblesnaturally contain air and thereby also oxygen gas. This oxygen gas doesnot have time to be flushed out but remains in the package. By insteadensuring that the package largely contains nitrogen gas on filling, thebubbles thus formed contain this gas instead. As a result, thesubsequent “head space flushing” stage will be more effective.

By discharging the gas in pulses, gas is consumed only when a package islocated beneath the supply means, which is extremely economical.

According to one preferred embodiment, the method includes the step ofpassing the supply means in the indexing step which is terminated whenthe package is located in the filling station.

Further, the method according to the present invention preferablyincludes the step of commencing said gas pulse when a first edge of thepackage substantially lies flush with the supply means so that the gasmay be caused to flow along a first inner side of the package. By suchmeans, it will be easier to evacuate the air which is located in thepackage, and this does not run the risk of remaining in the bottom ofthe package.

Preferably, the method according to the present invention furtherincludes the step of at the latest terminating said gas pulse when asecond edge of the package lies substantially flush with the supplymeans, this step is so as not to waste any gas unnecessarily.

According to one preferred embodiment of the method, this includes thestep of disposing the supply means on or in the proximity of the fillerpipe in such a manner that the package is caused to pass the supplymeans before passing the filler pipe. It is a very simple method todispose the supply means in the filling machine, and its positioningrequires no extra indexing step, and thereby takes up no extraprocessing time.

According to one preferred embodiment, the method according to theinvention comprises one step of employing an inert gas in the form ofnitrogen gas, and one step of supplying the gas at a first velocitythrough a first inner nozzle in the supply means and at a second, lowervelocity through a second surrounding outer nozzle. At high flow rates,eddies or currents are formed which “suck” in ambient gas. By ensuringthat the ambient gas is the same gas as that in the high flow rate, itis possible to prevent ambient air from being sucked down into thepackage. After all, the gas which is sucked down will instead come fromthe outer nozzle and it is that gas which is intended to get down intothe package.

The present invention also relates to an apparatus which includes supplymeans for an inert gas, the supply means being placed in the indexingdirection in the area between said filling station and the immediatelypreceding station in the filling machine. Said supply means are disposedto initiate a gas pulse in a direction down into the package when saidpackage passes beneath the supply means during transport to the fillingstation from the immediately preceding station.

One currently preferred embodiment of the apparatus according to thepresent invention is described in the appended dependent claims.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will now be described in greater detailhereinbelow, with the aid of one currently preferred embodiment which isshown in the accompanying Drawings. In the accompanying Drawings:

FIG. 1 schematically illustrates a number of stations included in afilling machine, as well as packages in a conveyor;

FIG. 2 schematically shows a view, partly in section, of the supplymeans and a package (which is in motion);

FIG. 3 schematically shows a cross section through the supply means; and

FIG. 4 schematically shows an isometric view of a part of the supplymeans.

It should be observed that the figures are not according to scale.

DETAILED DESCRIPTION OF ONE EMBODIMENT

FIG. 1 shows a number of stations A-F which are included in a part of afilling machine. At least partly formed packages, which are hereby givenreference numeral 10, arrive at station A. In the described embodiment,these packages are ready for filling. Normally, they are called“ready-to-fill” packages. In this case, the package 10 consists of blankof packaging laminate which has been reformed into a sleeve and sealedinto a tube form, and which has been sealed at a first end 12. Thissealing has been put into effect in that a packaging top with an openingarrangement or device has been injection moulded on the end of thesleeve. This is a known technique and will not be described further.Alternatively, the end of the sleeve has been folded and thermosealed. Asecond end 14 of the package 10 is still open and it is through thisopening that the package is to be filled with product in ordersubsequently to be sealed into a finished package. The term “tube form”is here to be interpreted broadly, i.e. all types of package crosssections are encompassed. Consequently, the package may, for example,have circular, triangular, square, rectangular or polygonal crosssection. In the example described here, the cross section is square.

The square packages are placed in a conveyor 16 for indexed, i.e.stepped, displacement into the filling machine. In the conveyor 16, thepackages are placed with their open end 14 most proximal the stationsA-F. In the described case, the top of the package 10 is therebydirected downwards in FIG. 1.

The conveyor may be of known type and will not be described in greaterdetail. Between stations A-F, which each constitute a separate processstage discrete from the others, there are one or more indexing steps.The number of steps depends upon the physical distance between thestations, and this distance is normally a multiple of the distance apackage is indexed at a time. For purposes of simplicity, in thedescribed example the distance between the stations is shown ascorresponding to only one indexing step, i.e. a package is indexeddirect from one station to the next. In reality, there may also be aplurality of stations of each type, where either all packages are eachadvanced stepwise to all stations (where they are subjected to a parttreatment, i.e. are filled stepwise), or where a number of packages areindexed together and, as a result, there is required a multiple of thedifferent stations in order for all packages to receive the sameprocessing.

Depending upon what type of package is involved, and whether or nottransport and storage of the package takes place in a refrigerated orunrefrigerated environment, the package may, at this stage, besterilised to an appropriate degree. Station A is a station is which asterilisation agent is supplied to the package 10. In this case, thesterilisation agent consists of hydrogen peroxide (H₂O₂) in lowconcentration. In this application, a 1 percent concentration isemployed. The hydrogen peroxide is supplied in the gas phase with theaid of nozzles and condenses on the inside of the package. The packageis then indexed one or more steps in the direction of the arrow (P) fromright to left in FIG. 1, to station B. Station B is a station where oneor more UV lamps are placed. The ultraviolet light is directed down intothe package. Both the hydrogen peroxide and the UV lamp realisedestruction of bacteria and it is known in the art that hydrogenperoxide and ultraviolet light give synergy effects in sterilisationcontexts. From station B, the package is indexed to station C which is aventilation station of known type. Here, warm, filtered clean air isblown down into the package for the purpose of ventilating off anypossibly remaining hydrogen peroxide. Preferably, an air filter of theH.E.P.A. type may be employed.

The package is thereby ready to be filled with product. The package isindexed to a filling station, station D. Between this station andstation C, along the indexing line, there is positioned a gas supplymeans 18. In the currently preferred and described example, the gassupply means 18 is placed on the filling station, more precisely securedon the filler pipe 20. Thus, the filler pipe 20 and the gas supply means18 are substantially parallel with one another and directed towards theopen package ends.

During the indexing to the filling station D, the package passes underthe gas supply means 18. The term passes is here taken to signify thatthe package does not stop beneath said means, but is in motion. This isbecause the means is placed in the indexing step, or as it were“between” indexing steps. The construction and operation of the gassupply means 18 will be described later in this specification.

When the package 10 at length reaches the filling station D, and hasbeen substantially centred beneath the filler pipe 20, filling ofproduct into the package 10 commences. The filling station D is of knowntype and will not be described further. If filling takes place in steps,i.e. if a partial quantity of the product is filled into the packagewith the aid of a first filling station D and the remaining quantityfilled with the aid of additional filling stations D, the gas supplymeans 18 is positioned in association with the first station D.

After the filling, the package is indexed to station E where anypossible froth in the product is given the opportunity to settlesomewhat. Here, a plate 22 is positioned with a nozzle a slight distancefrom the open end of the package. The plate 22 is preferably ofapproximately the same size and configuration as the opening of thepackage, in order approximately to serve as a “lid” over the opening.Through the nozzle, nitrogen is fed to the gas volume which is to befound above the surface of the product in the open end 14 of the package10, i.e. a “head space flushing” is carried out. The package 10 is thenindexed further to a sealing station F where an additional “head spaceflushing” is carried out, at the same time as the package is folded andsealed. A nozzle injects nitrogen gas in the sealing region, and anypossible remaining oxygen gas is “flushed” out. The sealing proper ofthe end of the package may be put into effect in a conventional manner.

With reference to FIG. 2, the gas supply means 18 and its function willnow be described in greater detail. The means 18 is operative toinitiate a gas pulse when a first edge 24 of the package arrivessubstantially flush with the supply means 18, see FIG. 2. The means 18is also operative to terminate the gas pulse when a second edge 26 ofthe package 10 arrives substantially flush with the supply means 18. Thefirst edge 24 of the package is that edge which first passes the gassupply means 18, and the second edge 26 is that edge which passes thegas supply means 18 last. The means 18 includes devices for initiatingand terminating the gas pulse. In this case, these devices consist of avalve 28, preferably a pneumatic valve, which is seen highlyschematically in FIG. 3 and which is in communication with the programmecontrolling the filling machine. The valve 28 opens a gas flow out ofthe gas supply means 18 substantially when the first edge 24 passes thesupply means 18, and closes the flow substantially when the second edge26 passes. In such means, a gas pulse is formed when the package 10passes beneath the supply means 18 and, since it is initiated alreadywhen the first edge 24 of the package 10 passes, there will be generateda gas flow substantially along or in the proximity of the inner side ofthe first edge. The air in the package 10 is then forced up along theopposite inner side and departs from the package. The flow isillustrated by means of single arrows in FIG. 2. The double-headed arrowillustrates the direction of movement of the package. In order toachieve a relatively high velocity of the flow, the gas is pressurisedto approximately 3 bar in the system ahead of the valve 28.

It has been described that the gas pulse is initiated when the supplymeans 18 “substantially arrives flush with” the first edge 24 of thepackage. Seen in the indexing direction, this implies that the pulse maystart either just before the edge 24 passes into the contemplatedoperative area 25 of the supply means (where the gas is disposed toflow), or when the edge is located somewhere within the operative area25 of the means, or when the edge 24 exactly passes into the operativearea 25 of the means or just after the edge 24 has passed out of theoperative area 25 of the supply means. In order to obtain a highlyeffective pulse and not consume more gas than necessary, it is to bepreferred if the gas pulse is discharged when the edge 24 of the packagejust passes out of the operative area 25 of the supply means, see FIG.2. The pulse is terminated when the supply means 18 “substantiallyarrives flush with” the second edge 26 of the package. This implies,seen in the indexing direction, that the pulse may be terminated eitherwhen the edge 26 has not yet passed into the operative area 25 of thesupply means, or when the edge 26 precisely passes into the operativearea 25, or when the edge 26 is located somewhere within the operativearea 25 of the supply means, or when the edge 26 has passed theoperative area 25 of the supply means. It is to be preferred if thepulse is terminated when the edge 26 precisely passes into the operativearea 25, by such means no gas is wasted unnecessarily.

The gas is inert and, in the described example, use is made of nitrogengas of accepted food quality. The valve 28 is in communication with anitrogen gas source (not visible).

Naturally, the pulse may be of longer or shorter duration in time thanthat described, if so desired. However, it is desirable that as littlenitrogen gas is wasted outside the package 10 as possible. The start andlength of the gas pulse is programmed in the machine, i.e. the fillingmachine is programmed to “know” when a package 10 passes under thesupply means 18. One alternative is to provide some form of sensor whichsenses the first and second edge 24 and 26 and which communicates withthe valve 28.

Below the valve 28, the supply means 18 consists of a first inner nozzle30 and a second, surrounding outer nozzle 32, see FIGS. 3 and 4.Consequently, the inner nozzle 30 is placed in the outer nozzle 32 andis disposed to supply gas at a first velocity. The outer nozzle 32 isdisposed to supply gas at a second, lower velocity. The difference invelocity is realised in that there is at least one passage 34 betweenthe inner nozzle 30 and the outer nozzle 32 where gas from the innernozzle may exist into the outer nozzle and thence further out of thesupply means 18. Both of the nozzles 30, 32 are tubular, and the innernozzle has a smaller diameter than the outer. In its one end, the innernozzle 30 is in communication with the valve 28 and the gas may rushstraight through the nozzle 30 and out through its free end, i.e. themouth of the nozzle. However, a small proportion of the gas existsthrough the above-mentioned passages 34 instead. The passages 34 areforaminations or holes through the wall of the inner nozzle a distancefrom the mouth. The holes are preferably obliquely outwardly anddownwardly directed. Preferably, a plurality of holes are uniformlydistributed about the periphery of the tube in order to afford a uniformflow of gas out in the outer nozzle 32. The outer nozzle is not incommunication with the valve 28, but, as was mentioned above, receivesits supply of gas through the holes 34. Said holes 34 discharge in anupper region of the outer nozzle 32, and the gas flows downwards in thetube towards its mouth which is located on the same height as the mouthof the inner nozzle. The opposite end of the outer nozzle is closed bymeans of a wall 36.

Both of the mouths of the inner and outer nozzle 30 and 32,respectively, are located in a direction towards the open end of thepackage.

Hence, the function of the gas supply means 18 will be as follows: Whenthe package 10 is conveyed to the filling station D from the immediatelypreceding station, which in this case is station C, it passes under thesupply means 18. At that instant when the first edge 24 of the package10 substantially arrives flush with the supply means 1, the valve 28 isopened and a gas pulse is initiated through the supply means 18. The gasmay flow along the inside of the package 10 and force out the air fromthe package 10. As soon as the second edge 26 passes the supply means18, the pulse is terminated in that the valve 22 shuts off the gas flow.The package has then completely passed the supply means 18 and stoppedin the filling station, where the filling commences.

If there is more than one indexing step between station C and D, the gassupply means should be positioned so that it is passed in the indexingstep which is terminated by the package 10 being located in station D.

The present invention has been described in the foregoing with the aidof one currently preferred embodiment. However, it should be understoodthat the present invention is not restricted to this embodiment, butthat numerous variations and modifications are possible withoutdeparting from the scope of the appended Claims. It has been describedthat the gas which is employed is to be inert so as not to react withthe product in the package. However, there are practical applicationswhere it is desirable to use gas which is to neutralise substances whichthe product may emit. The effect which it is intended to achieve isthereby substantially the same. It should be observed that also thistype of gas is incorporated in the term “inert gas”, even though it isnot inert in the true sense.

1. A method of reducing a proportion of oxygen in an at least partlyformed package before product is filled into said package in a fillingstation in a filling machine, where said package comprises a tub-formedblank of packaging material, the blank being closed in a first end andopen in a second end, the method comprises the steps of comprising:passing the package, during transport of the package to said fillingstation from an immediately preceding station in the filling machine,beneath supply means for inert gas, and generating, when the packagepasses said supply means, a gas pulse in a direction down into saidpackage.
 2. The method as claimed in claim 1, further comprising passingthe supply means in that indexing step which is terminated by a packagebeing located in the filling station.
 3. The method as claimed in claim1, further comprising commencing said gas pulse when a first edge of thepackage substantially arrives flush with the supply means so that thegas flows along a first inner side of the package.
 4. The method asclaimed in claim 1, further comprising terminating said gas pulse when asecond edge of the package substantially arrives flush with the supplymeans.
 5. The method as claimed in claim 1, further comprising disposingthe supply means on or in proximity of a filler pipe, which fills theproduct in the package, in such a manner that the package passes thesupply means before passing the filler pipe.
 6. The method as claimed inclaim 1, further comprising employing nitrogen gas as the inert gas. 7.The method as claimed in claim 1, wherein the gas is supplied at a firstvelocity through a first inner nozzle of the supply means and at asecond, lower velocity through a second surrounding outer nozzle.
 8. Anapparatus for reducing proportion of oxygen in an at least partly formedpackage before product is filled into said package in a filling stationin a filling machine, the package comprising a tube-shaped blank ofpackaging material, the blank being closed in a first end and open in asecond end, the apparatus comprising supply means for an inert gas, saidsupply means being placed in the indexing direction in the regionbetween said filling station and an immediately preceding station in thefilling machine; and said supply means is adapted to initiate a gaspulse in a direction down in the package when said package passesbeneath the supply means during transport to the filling station from animmediately preceding station.
 9. The apparatus as claimed in claim 8,wherein said supply means is disposed such that said package passesbeneath the supply means in an indexing step which is terminated by thepackage being located in the filling station.
 10. The apparatus asclaimed in claim 8, wherein the apparatus further includes means forinitiating the gas pulse when a first edge of the package substantiallyarrives flush with the supply means so that the gas may be caused toflow along a first inner side of the package.
 11. The apparatus asclaimed in claim 10, wherein said means is also disposed to terminatethe gas pulse when a second edge of the package substantially arrivesflush with the supply means.
 12. The apparatus as claimed in claim 8,wherein said immediately preceding station is a sterilisation stationwhich, in an indexing direction, includes a station for supply of asterilisation agent, a station for supply of UV light, and a station forsupply of hot air for ventilating out residues of the sterilisationagent.
 13. The apparatus as claimed in claim 8, wherein said supplymeans includes a first inner nozzle and a second, surrounding outernozzle, where the inner nozzle is disposed to supply gas at a firstvelocity, and where the outer nozzle is disposed to supply gas at asecond, lower velocity.
 14. The apparatus as claimed in claim 13,wherein both of the nozzles are tubular, the inner nozzle is providedwith at least one through-going hole a distance from a mouth of theinner nozzle, and a part of the gas which flows through the inner nozzleflows through the hole to the outer nozzle and departs from the supplymeans through a mouth of the outer nozzle.
 15. The apparatus as claimedin claim 8, wherein the supply means is disposed on or in proximity ofthe filler pipe in such a manner that the package is caused to pass thesupply means before passing the filler pipe.
 16. The apparatus asclaimed in claim 8, wherein the gas is nitrogen gas.